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1.
Several p H-dependent processes and reactions take place in the human body;hence,the p H of body fluids is the best indicator of disturbed health conditions.However,accurate and real-time diagnosis of the p H of body fluids is complicated because of limited commercially available p H sensors.Hence,we aimed to prepare a flexible,transparent,disposable,userfriendly,and economic strip-based solid-state p H sensor using palladium nanoparticles(Pd NPs)/N-doped carbon(NC)composite material.The Pd NPs/NC composite material was synthesized using wool keratin(WK)as a precursor.The insitu prepared Pd NPs played a key role in the controlled switching of protein structure to the N-doped carbon skeleton withπ–πarrangement at the mesoscale level,which mimics the A–B type polymeric structure,and hence,is highly susceptible to H+ions.The optimized carbonization condition in the presence of Pd NPs showed that the material obtained using a modified Ag/Ag Cl reference electrode had the highest p H sensitivity with excellent stability and durability.The optimized p H sensor showed high specificity and selectivity with a sensitivity of 55 m V/p H unit and a relative standard deviation of 0.79%.This study is the first to synthesize Pd NPs using WK as a stabilizing and reducing agent.The applicability of the sensor was investigated for biological samples,namely,saliva and gastric juices.The proposed protocol and material have implications in solid-state chemistry,where biological material will be the best choice for the synthesis of materials with anticipated performance.  相似文献   
2.
Diastereo‐ and enantioselective cycloaddition of 3‐nitroindoles with vinyl aziridine was realized under Pd‐catalysis using commercially available Walphos as the ligand, affording pyrroloindolines in high yields with high diastereo‐ and enantioselectivities. The reaction can be scaled up to a gram scale and the reaction products are easily converted to amino pyrroloindoline and other pyrroloindoline derivatives.  相似文献   
3.
In this work, an easily obtained procedure was successfully implemented to prepare novel palladium nanoparticles decorated on triethanolammonium chloride ionic liquid‐functionalized TiO2 nanoparticles [TiO2/IL‐Pd]. Different methods were carried out for characterizations of the synthesized nanocatalyst (HR‐TEM, XPS, XRD, FE‐SEM, EDX, FT‐IR and ICP). TiO2/IL‐Pd indicated good catalytic activity for the Suzuki–Miyaura cross‐coupling reaction of arylboronic acid with different aryl halides in aqueous media at ambient temperature. The recycled catalyst was investigated with ICP to amount of Pd leaching after 6 times that had diminished slightly, Thus, was confirmed that the nanocatalyst has a good sustainability for C–C Suzuki–Miyaura coupling reaction. The catalyst can be conveniently separated by filtration of the reaction mixture and reused for 6 times without significant loss of its activity. It supplies an environmentally benign alternative path to the existing protocols for the Suzuki–Miyaura reaction.  相似文献   
4.
甲醇选择氧化制备甲酸甲酯(MF)是延伸甲醇产业链、开发高附加值下游产品的有效途径之一,负载型Au及Pd催化剂在这一反应中表现出优异的低温催化性能。为探索实用、高效和易再生的甲醇选择氧化催化剂,同时揭示双金属颗粒中Au和Pd的协同效应及甲醇氧化反应机理,本研究制备了一系列二氧化硅负载的Au-Pd催化剂(Au-Pd/SiO2),详细研究了其对甲醇选择氧化制甲酸甲酯的催化性能。结果表明,Au和Pd总负载量为0.6%、且Au/Pd质量比为2时,所制备的Au2-Pd1/SiO2催化剂表现出优异的甲醇氧化催化性能;在130℃下,甲醇转化率达到57.0%,MF选择性为72.7%。多种表征结果显示,Au-Pd双金属纳米颗粒粒径为2-4 nm,高度分散于SiO2载体表面,倾向于生成孪晶结构并暴露(111)晶面,这些因素是Au-Pd/SiO2具有优异催化性能的主要原因。通过DRIFTS表征研究,提出了一个可能的MF生成机理:即甲醇首先与处于Au-Pd纳米粒子界面的表面氧作用,生成化学吸附的甲氧基;随后,甲氧基经去质子作用生成吸附的甲醛物种,后者与相邻的甲氧基物种亲核反应,并经β-H消除后得到目标产物MF。  相似文献   
5.
The construction of DNA‐encoded chemical libraries (DECLs) crucially relies on the availability of chemical reactions, which are DNA‐compatible and which exhibit high conversion rates for a large number of diverse substrates. In this work, we present our optimization and validation procedures for three copper and palladium‐catalyzed reactions (Suzuki cross‐coupling, Sonogashira cross‐coupling, and copper(I)‐catalyzed alkyne‐azide cycloaddition (CuAAC)), which have been successfully used by our group for the construction of large encoded libraries.  相似文献   
6.
7.
采用固相-液相两步混合法制备了由碳纳米管(CNTs)和石墨烯纳米片(GNPs)组成的CNTs-GNPs复合载体。以乙二醇还原法将Pd纳米粒子沉积于复合碳载体上,制得Pd/CNTs-GNPs催化剂。以透射电子显微镜、X射线衍射及X射线光电子能谱表征催化剂的形貌、组成和结构;以电化学方法考察催化剂的甲醇电氧化性能。结果表明,Pd/CNTs-GNPs(1/4)(GNPs质量分数为1/4)催化剂具有较大的电化学表面积和较高的甲醇电氧化活性,其甲醇氧化峰电流密度可达Pd/CNTs催化剂的1.97倍。催化剂的高活性得益于CNTs-GNPs载体的一维/二维复合结构使Pd纳米粒子具有良好的分散性能。计时电流实验表明,与单一载体负载Pd催化剂相比,复合载体负载Pd催化剂具有较强的抗中毒能力。  相似文献   
8.
A novel nanocatalyst was designed and prepared. Initially, the surface of magnetic graphene oxide (M‐GO) was modified using thionyl chloride, tris(hydroxymethyl)aminomethane and acryloyl chloride as linkers which provide reactive C═C bonds for the polymerization of vinylic monomers. Separately, β‐cyclodextrin (β‐CD) was treated with acryloyl chloride to provide a modified β‐CD. Then, in the presence methylenebisacrylamide as a cross‐linker, monomers of modified β‐CD and acrylamide were polymerized on the surface of the pre‐prepared M‐GO. Finally, palladium acetate and sodium borohydride were added to this composite to afford supported palladium nanoparticles. This fabricated nanocomposite was fully characterized using various techniques. The efficiency of this easily separable and reusable heterogeneous catalyst was successfully examined in Suzuki–Miyaura cross‐coupling reactions of aryl halides and boronic acid as well as in modified Suzuki–Miyaura cross‐coupling reactions of N‐acylsuccinimides and boronic acid in green media. The results showed that the nanocatalyst was efficient in coupling reactions for direct formation of the corresponding biphenyl as well as benzophenone derivatives in green media based on bio‐based solvents. In addition, the nanocatalyst was easily separable, using an external magnet, and could be reused several times without significant loss of activity under the optimum reaction conditions.  相似文献   
9.
A palladium-catalyzed enantioselective redox-relay Heck reaction of 2-indole triflates and disubstituted alkenes is reported. This process combines readily available indole triflates with a variety of alkenes to afford a range of indole derivatives bearing a stereocenter adjacent to C2. Enantioselectivity is achieved through use of a simple pyridine-oxazoline ligand. Tuning the electronics of the indole, through judicious choice of N-protecting group, is required to ensure selective β-hydride elimination away from the indole core. Utility of this method is highlighted in a modular formal synthesis of an S1P1 agonist precursor developed by Merck.  相似文献   
10.
LDH/Tris/Pd (CaAl‐layered double hydroxide/tris (hydroxymethyl)aminomethane/palladium) was synthesized and appraised for its catalytic activity towards the degradation of two selected azo dyes. The decolorization of azo dyes, acid red 18 (AR 18) and reactive yellow 15 (RY 15), requires considerably small amounts of synthesized catalyst. Kinetic studies show that the catalytic decolorization of these azo dyes follows the first order kinetic model. The reported method is simple and applicable; in addition, the stable catalyst can efficiently decolorize model azo dyes with good recyclability. Therefore, LDH/Tris/Pd can be accepted as the possible component for the utilization in wastewater treatment.  相似文献   
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